Jet-weaving machines, particularly air jet-weaving machines, belong to shuttleless weaving machines. A shuttleless weaving machine of this type is known from DE 32 00 638 A1. In this known shuttleless weaving machine, either a thread clamp is arranged in the end region of the mixing tube of a main blow nozzle mounted on the batten or, in addition to this, a further thread clamp is arranged upstream of the entry of the weft thread into the main blow nozzle. The known thread clamps are designed as an elastic intermediate piece which is inserted firmly into the mixing tube and which by means of linearly movable lifting members can clamp the weft thread essentially in the middle of the mixing tube. Furthermore, clamping devices are described which operate by means of linearly movable lifting members which are arranged with a close fit in the intermediate tube and which clamp the weft thread on an opposite wall of the mixing tube flattened in cross section in the region of the orifice of issue. The movement of the lifting members which is necessary for generating the clamping action of the thread clamps requires relatively long stroke travels, since they execute a linear movement.
Furthermore, DE 102 44 694 A1 discloses a method for holding a weft thread in the region of a main nozzle of a jet-weaving machine and a jet-weaving machine for carrying out the method. In this known jet-weaving machine, a clamping device in the form of a pneumatic muscle in the front region, that is to say the fabric-confronting outlet end of the mixing tube is described. The pneumatic muscle described is acted upon with compressed air from outside, with the result that its walls are pressed toward the middle of the mixing tube, in which region the weft thread to be clamped is located. The weft thread is thereby clamped approximately in the region of the longitudinal axis of the mixing tube.
Furthermore, a weft-thread tensioning device for a main nozzle device of an air jet-weaving machine is known from DE 102 57 035 A1. In this known air jet-weaving machine, in each case a thread clamp is arranged upstream of the main nozzle device and downstream of the main nozzle device in the region of the end of the mixing tube. On the one hand, the clamping device described is activated by linearly movable actuators, for which relatively long stroke travels are required in order to implement the clamping movement. On the other hand, the disadvantage of clamping the weft thread even upstream of the main nozzle is that clamping imparts to the weft thread a pinch which no longer readily comes loose in the case of specific materials after the insertion of the weft thread, so that this clamping can be detected at least visually in the finished fabric. In order to avoid clamping traces of this kind being visible in the finished fabric, a relatively large amount of waste, that is to say the end to be cut off from the weft thread, would have to be taken into account. This, however, would result in a relatively high loss of material.
Finally, a device for holding the weft thread at the exit of the mixing tube of a main blow nozzle is known from JP 2000119936.
The clamping surface of a clamping lever loaded, for example, by a spring engages into a longitudinal groove present on the end face in the mixing tube and at the same time takes effect positively on an abutment likewise present on the end face of the mixing tube. The weft thread is in this case clamped between the clamping surface and the abutment.
The clamping lever is designed in such a way that the air stream of the main blow nozzle which transports the weft thread acts upon the clamping lever counter to the action of its clamping force and opens and in this case at the same time releases the weft thread clamped between the clamping surface and abutment.
An individual control of the clamping or holding device is not possible.